| 31. |
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| 32. |
- Akre [Fall], Katja, 1971-, et al.
(författare)
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Risk for gastric cancer after antibiotic prophylaxis in patients undergoing hip replacement
- 2000
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Ingår i: Cancer Research. - Birmingham, USA : American Asoociation for Cancer Research. - 0008-5472 .- 1538-7445. ; 60, s. 6376-
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Tidskriftsartikel (refereegranskat)abstract
- Despite strong evidence of an association between Helicobacter pylori and gastric cancer, the benefit of eradicating H. pylori infection is unknown. Our aim was to test the hypothesis that exposure to high doses of antibiotics reduces risk for gastric cancer via possible eradication of H. pylori We conducted a nationwide case-control study nested in a cohort of 39,154 patients who underwent hip replacement surgery between 1965 and 1983. Such patients frequently receive prophylactic antibiotic treatment. During follow-up through 1989, we identified 189 incident cases of gastric cancer. For each case, three controls were selected from the cohort. Exposure data were abstracted from hospital records. Blood samples from a separate cohort undergoing hip replacement surgery were analyzed for anti-H. pylori IgG before and after surgery. Both long-term antibiotic treatment before surgery [odds ratio (OR), 0.3; 95% confidence interval (CI), 0.1-0.7] and prophylactic antibiotic treatment (OR, 0.7; 95% CI, 0.5-1.1) conferred a reduction in gastric cancer risk. The reduction appeared stronger after 5 years (OR, 0.6; 95% CI, 0.3-1.2) than during shorter follow-up after hip replacement (OR, 0.8; 95% CI, 0.4-1.7). There was an apparent decrease in risk with increasing body weight-adjusted doses of antibiotics (P = 0.13). However, the rate of H. pylori antibody disappearance was not strikingly higher in the cohort of patients undergoing hip replacement than in a control cohort. Our findings provide indirect support for the hypothesis that treatment with antibiotics at a relatively advanced age reduces the risk of gastric cancer.
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| 33. |
- Akre, Olof, et al.
(författare)
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Epstein-Barr virus and cytomegalovirus in relation to testicular-cancer risk : a nested case-control study
- 1999
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Ingår i: International Journal of Cancer. - 0020-7136 .- 1097-0215. ; 82:1, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- An infectious etiology of testicular cancer has been suggested. We have evaluated seroreactivity against cytomegalovirus (CMV) and Epstein-Barr virus (EBV) in relation to testicular-cancer risk in a case-control study, nested within a cohort of prospectively collected serum specimens from 293,692 individuals. For each of 81 cases of testicular cancer identified, 3 controls were randomly selected from the cohort. Serum IgG antibody titers against CMV and EBV were determined using enzyme-linked immunosorbent assays (ELISAs) and immunofluorescence methods. Odds ratios (OR) were obtained from conditional logistic-regression models. No association was found between CMV positivity and testicular cancer overall (OR = 1.08; 95% confidence interval 0.60-1.94); risk for testicular seminoma was increased among CMV seropositive [OR = 1.70 (0.80-3.59)], whereas seropositivity was associated with decreased risk for testicular non-seminoma [OR = 0.54 (0.19-1.56)] (p for heterogeneity, 0.09). For EBV, the risk for testicular cancer was increased among individuals seropositive for viral capsid antigen (VCA) [OR = 2.74 (0.62-12.12)]. The results lend some support to the hypothesis of an infectious etiology, and we propose that future studies should take into account age at infection.
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| 34. |
- Alimohammadzadeh, Rana, et al.
(författare)
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Improving the mechanical properties of CTMP fibers by combining synergistic organocatalytic/polyelectrolyte complex surface engineering with sulfite pretreatment
- 2022
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Ingår i: Proceedings of the International Mechanical Pulping Conference. ; , s. 149-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Fabrication of paper-based packaging materials is increasing and the challenge is developing a sustainable process to manufacture the materials that can compete with plastics. Employing stronger fiber in production of fiber-based materials improves the efficiency of fabrication process by using a reduced amount of biomass. Cationic starch is a well-known polysaccharide that has been introduced to paper and paperboard fibers to improve the mechanical properties of lignocellulosic fibers. The polyelectrolyte (PE) multilayer method has been popularized as a new and interesting technique to enhance the adsorption of cationic starch on the fiber for improving the strength properties of chemi-thermomechanical pulp (CTMP), chemical and kraft pulps. We have shown in our previous work that the synergistic combination of organocatalysis and PE complexes improved the mechanical properties of CTMP and TMP. In this work, we chose to expand this concept by integrating it with low-dose sulfite pretreatment of wood chips in preparation of CTMP. Thus, CTMP produced by initial sulfite pre-treatment was next surface engineered by synergistic combination of organocatalysis and PE complexes using organic acids as catalysts. The CTMP pulps, which contains 0.1-0.24 wt.% sulfur, produced by our novel pulp-engineering strategy shows a dramatic strength increase (Z- strength: up to 100 %) as compared to no surface engineering. While only sulfite pre-treatment and PE-complex surface engineering were able to improve the strength properties, it was only when the organic catalysts was present that the highest strength improvements were reached. Thus, a clear synergistic effect of the catalyst was observed.
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| 35. |
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| 36. |
- Andres, Sonke, et al.
(författare)
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Type I Restriction-Modification Loci Reveal High Allelic Diversity in Clinical Helicobacter pylori Isolates
- 2010
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Ingår i: Helicobacter. - : Wiley. - 1083-4389 .- 1523-5378. ; 15:2, s. 114-125
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Tidskriftsartikel (refereegranskat)abstract
- Background: A remarkable variety of restriction-modification (R-M) systems is found in Helicobacter pylori. Since they encompass a large portion of the strain-specific H. pylori genes and therefore contribute to genetic variability, they are suggested to have an impact on disease outcome. Type I R-M systems comprise three different subunits and are the most complex of the three types of R-M systems. Aims: We investigated the genetic diversity and distribution of type I R-M systems in clinical isolates of H. pylori. Material and methods: Sixty-one H. pylori isolates from a Swedish hospital based case-control study and 6 H. pylori isolates of a Swedish population-based study were analyzed using polymerase chain reaction for the presence of the three R-M systems' subunits. Representative gene variants were sequenced. Results: Although the hsdM and hsdR genes appeared conserved in our clinical H. pylori isolates, the sequences of the hsdS loci were highly variable. Despite their sequence diversity, the genes per se were present at high frequencies. We identified a number of novel allelic hsdS variants, which are distinct from corresponding hsdS loci in the sequenced H. pylori strains 26695, J99 and HPAG1. In analyses of paired H. pylori isolates, obtained from the same individuals with a 4-year interval, we observed genetic modifications of hsdS genes in patients with atrophic gastric mucosa. Discussion: We propose that the genetic variability of hsdS genes in a bacterial population will give rise to new specificities of these enzymes, which might lead to adaptation to an ever-changing gastric environment.
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| 37. |
- Aspholm, Marina, et al.
(författare)
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SabA is the H. pylori hemagglutinin and is polymorphic in binding to sialylated glycans.
- 2006
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Ingår i: PLoS pathogens. - : Public Library of Science (PLoS). - 1553-7374 .- 1553-7366. ; 2:10
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Tidskriftsartikel (refereegranskat)abstract
- Adherence of Helicobacter pylori to inflamed gastric mucosa is dependent on the sialic acid-binding adhesin (SabA) and cognate sialylated/fucosylated glycans on the host cell surface. By in situ hybridization, H. pylori bacteria were observed in close association with erythrocytes in capillaries and post-capillary venules of the lamina propria of gastric mucosa in both infected humans and Rhesus monkeys. In vivo adherence of H. pylori to erythrocytes may require molecular mechanisms similar to the sialic acid-dependent in vitro agglutination of erythrocytes (i.e., sialic acid-dependent hemagglutination). In this context, the SabA adhesin was identified as the sialic acid-dependent hemagglutinin based on sialidase-sensitive hemagglutination, binding assays with sialylated glycoconjugates, and analysis of a series of isogenic sabA deletion mutants. The topographic presentation of binding sites for SabA on the erythrocyte membrane was mapped to gangliosides with extended core chains. However, receptor mapping revealed that the NeuAcalpha2-3Gal-disaccharide constitutes the minimal sialylated binding epitope required for SabA binding. Furthermore, clinical isolates demonstrated polymorphism in sialyl binding and complementation analysis of sabA mutants demonstrated that polymorphism in sialyl binding is an inherent property of the SabA protein itself. Gastric inflammation is associated with periodic changes in the composition of mucosal sialylation patterns. We suggest that dynamic adaptation in sialyl-binding properties during persistent infection specializes H. pylori both for individual variation in mucosal glycosylation and tropism for local areas of inflamed and/or dysplastic tissue.
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| 38. |
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| 39. |
- Atuma, Christer, et al.
(författare)
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Extracts of Helicobacter pylori reduce gastric mucosal blood flow through a VacA- and CagA-independent pathway in rats
- 1998
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 33:12, s. 1256-1261
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Helicobacter pylori may interfere with gastroduodenal protective mechanisms. Such effects could be due to a direct interaction with gastric epithelial cells but also to the action of a wide range of secreted and membrane-bound virulence factors. Our aim was to study the acute effects of water extracts produced from H. pylori on gastric mucosal blood flow and acid secretion and to relate them to VacA and CagA activity.METHOD: Extracts were produced from strains 88-23 and A5, both wild type; A5VacA, an isogenic mutant lacking expression of the vacuolating cytotoxin (VacA) and the immunodominant antigen (CagA); and Escherichia coli strain ATCC-25922. Bacterial extracts were applied on the exteriorized gastric corporal mucosa in inactin-anaesthetized rats after removal of as much as possible of the mucus layer, during intravital microscopy. Blood flow was measured by means of laser-Doppler flowmetry.RESULTS: All H. pylori extracts, including the extract from 88-23 heated to 100 degrees C for 30 min, significantly reduced blood flow by 15%-19%, whereas E. coli had no significant effect on blood flow.CONCLUSION: A factor or a combination of factors, other than VacA and CagA released from H. pylori, might compromise the natural defence of the gastric corporal mucosa by reducing mucosal blood flow. The factor is heat-stable and lacking or less potent in E. coli.
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| 40. |
- Atuma, C, et al.
(författare)
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Helicobacter pylori extracts reduce gastric mucosal blood flow by a nitric oxide-independent but mast cell- and platelet-activating factor receptor-dependent pathway in rats
- 1999
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 34:12, s. 1183-1189
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: We have previously shown that water extracts from Helicobacter pylori reduce gastric mucosal blood flow by approximately 15%. It has also been suggested that H. pylori can inhibit endogenous nitric oxide (NO) biosynthesis. Our aim was to examine whether the reduction in blood flow induced by H. pylori is the direct consequence of an NO synthase inhibition and the possible involvement of mast cell degranulation.METHODS: A water extract was produced from wildtype strain 88-23. The extract was applied on the exteriorized gastric corporal mucosa in inactin-anesthetized rats, after removing as much as possible of the mucus layer, during intravital microscopy. Blood flow was measured with laser-Doppler flowmetry.RESULTS: In rats pretreated with the NO synthase inhibitor N-nitro-L-arginine there was a 19% +/- 6% reduction in blood flow 40 min after application of the extract, and a 27% +/- 9% reduction after another 20 min with saline. The reduction was abolished by concomitant pretreatment with the mast cell stabilizer ketotifen or the platelet-activating factor (PAF) receptor antagonist WEB2086.CONCLUSION: The reduction in mucosal blood flow induced by the extract was probably mediated through an acute inflammatory response involving mast cell degranulation with consequent PAF secretion. The effect on blood flow was not the result of a decrease in vascular tone due to an inhibition of endogenous NO biosynthesis.
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